The problem is that the required handshaking from the S97 to your AVR and then to the MT700 is not making the round trip. You do have to turn on the equipment in the correct order, starting with the S97, then the AVR and finally the MT700.
The key is that you did say that going from the S97 directly to the MT700 "takes some time" to recognize the connection (implies that the S97 signal is barely strong enough for the MT700). Adding the extra connection, adds enough impedance in the path to disrupt the handshaking signal.
The key is that you did say that going from the S97 directly to the MT700 "takes some time" to recognize the connection (implies that the S97 signal is barely strong enough for the MT700). Adding the extra connection, adds enough impedance in the path to disrupt the handshaking signal.













